Crunchbase - Crunchbase is a platform for discovering industry trends, investments, and news about companies around the world.
LinkChecker - LinkChecker is a free, GPL licensed website validator.
CB Insights - CB Insights is a company database for the venture capital and corporate development community.
Dead Link Checker - Check for broken links on any website
Owler - Owler is a crowdsourced data model allowing users to follow, track, and research companies.
Pulno - SEO Audit and Website Analysis. Pull up your SEO.